nickd Posted July 31, 2007 Report Share Posted July 31, 2007 Hello Folks, I've just bought a boat, 42' with Lister SR3. I'm still learning its steering foibles and am having a few problems and wonder if you can help. When I put the rudder hard over and put any reasonable thrust on the engine, instead of the prow moving in the required direction the wholeboat 'crabs' sideways in that direction; under low power it's fine but there are times that I need to quickly manouvre, eg tricky turn, winding or when there's a wind blowing etc etc When the survey was undertaken the surveyor said the boat had a smallish rudder, would this have any bearing on it? I would appreciate any advice. Regards, Nick Link to comment Share on other sites More sharing options...
howardang Posted July 31, 2007 Report Share Posted July 31, 2007 Hello Folks, I've just bought a boat, 42' with Lister SR3. I'm still learning its steering foibles and am having a few problems and wonder if you can help. When I put the rudder hard over and put any reasonable thrust on the engine, instead of the prow moving in the required direction the wholeboat 'crabs' sideways in that direction; under low power it's fine but there are times that I need to quickly manouvre, eg tricky turn, winding or when there's a wind blowing etc etc When the survey was undertaken the surveyor said the boat had a smallish rudder, would this have any bearing on it? I would appreciate any advice. Regards, Nick It sounds like the rudder is stalling - i.e. the prop thrust is flowing on each side of the rudder with the rudder hard over so as well as a turning component you are also getting more ahead thrust that you would normally expect. Try easing the rudder back towards amidships until you get maximum turning effect and then remember that setting for future use. HTH Howard Anguish Link to comment Share on other sites More sharing options...
DHutch Posted July 31, 2007 Report Share Posted July 31, 2007 Yeah, if nothing else, try it a little off full lock. - On most boats the rudder will move further than its optimum position. - Only emilyanne you get more turning half a turn off full lock, going left anyway. Daniel Link to comment Share on other sites More sharing options...
dor Posted July 31, 2007 Report Share Posted July 31, 2007 When turning such as winding, try wiggling the tiller and watch the wash coming out at the back. As you move the rudder from say 20 degrees to about 60 degrees you may see the wash split round the prop. If you keep wiggling slowly, if you are lucky you will suddenly see all the wash directed to the side instead of being split. It's all to do with something called "fluidics", and basically it's because the water likes to keep attached to a surface. It may not work if the rudder is too small or doesn't have enough balance area, but if you can catch the trick, it's amazing how easy you will be able to turn your boat. Get it right and you will be able to spin the boat practically in its own length. Link to comment Share on other sites More sharing options...
nickd Posted August 1, 2007 Author Report Share Posted August 1, 2007 Many thanks for the information. Regards, Nick Link to comment Share on other sites More sharing options...
DHutch Posted August 1, 2007 Report Share Posted August 1, 2007 And then we can move onto profiled rudders... Daniel Link to comment Share on other sites More sharing options...
Mr Baites Posted August 1, 2007 Report Share Posted August 1, 2007 wel a fink its ruder ridicoloos Link to comment Share on other sites More sharing options...
blackrose Posted September 24, 2007 Report Share Posted September 24, 2007 When the survey was undertaken the surveyor said the boat had a smallish rudder, would this have any bearing on it? Yes, it should have a bearing on the rudder stock! Sorry, I'll get me coat... Link to comment Share on other sites More sharing options...
John Orentas Posted September 24, 2007 Report Share Posted September 24, 2007 (edited) When the survey was undertaken the surveyor said the boat had a smallish rudder, would this have any bearing on it? It should have two bearings on it: One top, one bottom. (Oh dear should have read the previous post). It could be too small, but more likely not enough 'balance blade', that's the extension forward of the rudder shaft. Also as Daniel says it may be a case of to just just to much rudder angle, experiment using less angle you may find an improvement, many boats are built like that. Edited September 24, 2007 by John Orentas Link to comment Share on other sites More sharing options...
zenataomm Posted September 24, 2007 Report Share Posted September 24, 2007 I agree with most of the replies (except about the bearings, I lost mine ages ago and haven't suffered at all ..... those around me have, but I'm ok) What is worth remembering is that narrow boats aren't really designed to be steered in reverse, it's there to stop you. There will always be the odd design that can do it, and those that can will be loud in their claims. They only do that to make us lesser mortals hang our heads in envy, and because they can! Yes of course the size of the rudder is important in order to get maximum efficiency as is the balance area. You will find as others have suggested that you'll get a feel for what works. The other thing that may be affecting the sideways crabbing motion is your engine. Listers, even 3 cylinder ones are still slow revving and throwing a lot of weight to one side. You'll not notice it when in ahead but when you change direction (ahead to astern) it'll make itself felt. You can prove this to yourself in a wide lock on your own. The boat is likely to show a preference to staying aginst one wall than the other, due to the rotation of the engine even on tickover. zenataomm Link to comment Share on other sites More sharing options...
JohnOnTheWey Posted September 24, 2007 Report Share Posted September 24, 2007 [snip]What is worth remembering is that narrow boats aren't really designed to be steered in reverse, it's there to stop you. There will always be the odd design that can do it, and those that can will be loud in their claims. [more snip] Who mentioned going in reverse? JOTW Link to comment Share on other sites More sharing options...
Maffi Posted September 24, 2007 Report Share Posted September 24, 2007 (edited) Who mentioned going in reverse? JOTW Well you have for one. Edited September 24, 2007 by Maffi Link to comment Share on other sites More sharing options...
bottle Posted September 24, 2007 Report Share Posted September 24, 2007 There is a short paragraph explanation about rudder angle at Tony's site TB training steering Link to comment Share on other sites More sharing options...
bristol & argo Posted September 25, 2007 Report Share Posted September 25, 2007 snip,a case of to just just to much rudder angle, snip, , many boats are built like that. And if you've got a full size boat, it can be quite important that it does, along with being able to lift the stern fenders so you can get through Caen Hill Hmm, those friends still haven't been back for another trip . simon. Link to comment Share on other sites More sharing options...
zenataomm Posted September 25, 2007 Report Share Posted September 25, 2007 Who mentioned going in reverse? JOTW I did!!!!!! ...... t'was me!........ I recognise that dribble anywhere! ........... but only because I wanted to create a tenuous link in order to start waffling about slow rotating engines with heavy flywheels that make boats go sideways when they lose way. Perhaps I lost my way! But that's not my fault, you really shouldn't let me on these forums , I can't be trusted you know? Anybody got any custard creams? Link to comment Share on other sites More sharing options...
carlt Posted September 25, 2007 Report Share Posted September 25, 2007 It's not actually true that narrowboats can't steer while going in reverse, they can, but not in reverse gear. Link to comment Share on other sites More sharing options...
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